Design of spiral staircases

Quick answer：

Spiral staircases are architectural elements characterized by a helical design that rises or descends in a circular pattern. They are commonly used in buildings for aesthetic appeal and space efficiency. Design considerations include the stair width, tread depth and riser height, as well as the overall shape and materials used. Spiral staircases can be made from various materials such as wood, metal, or concrete and may feature different styles like classical, modern, or minimalist.